Vertical-flue boiler



(No Model.)

0 AHRENS VERTICAL FLUB BOILER. No. 519,013.

Patented May 1, 1894.-

-3 a'a'afzz' UNITED STATES PATE T Erica, E

CHRISTOPHER AHRENS, OF CINCINNATI, OHIO, ASSIGN OR TO THE AMERI- CAN FIRE ENGINE COMPANY, OF SAME PLACE, AND SENECA FALLS,

NEW YORK.

VERTICAL-FLUE BOILER.

SPECIFICATION forming part of Letters Patent No. 519,013, dated May 1, 1894.

Application filedJuly 8,1893. Serial No. 479.872- (No m To aZZ whom it may concern:

Be it known that I, CHRISTOPHER AHRENS, a citizen of the United States, residing at Cincinnati, Ohio, have-invented new and useful Improvements in Vertical Flue Boilers, of which the following is a specification. I My invention relates to vertical tubular boilers of the type in which a central fire-box is embraced within the outer shell, with vertical lines opening through the crown sheet of the fire-box and the top or head of the boiler. In such boilers, especially those in which the number of fines opening through the crownsheet is large in proportion to its area,-being therefore set close together and crowding the water space,the intense heat concentrated at the crown-sheet tends to drivethe water away from the same. At the same time, the

forest of fines opening through and extending much as the supply is necessarily compelled to pass inward through the contracted space between the heated tubes and over the highly heatedcrown-sheet. Inboilers sooonstructed, priming, and the burning-out of crown-sheet and flue-ends, are the dangerous and inevitable results of heavy firing. As a remedy for this condition, circulation pipes have been introduced in the fire box, connecting the crown sheet and the water 7 1eg,usually curved tubes or a system of radially arranged tubes concentrated at a central vertical con nection entering the crown sheet. Such constructions are, however, found to be inefficient by reason of the great expansion caused by the intense heat to which they are exposed, and subsequent contraction by cooling, which soon destroys the efficiency of the joints; these defects being aggravated in some cases by the contact of the tubes themselves with the incandescent fuel of the fire-box, which injures the metal of the tubes. Moreover,

such constructions are expensive and difficult to repair, in that the forms of the connectiontubes are special and require great skill, and nicety of fit, and also because they can only be inserted by taking the boiler itself apartall of which causes delay and incidental expenses.

My improvement presents a complete remedy for these difficulties: and consists in a cir- 7 return bend connected at one free end by an elbow and vertical pipe with the crownsheet, and at the other'by an elbow and horizontal pipe with the water-leg. The construction is entirely made up of straight sections of pipe with elbows and a U-bend, secured in the usual manner, and screw-threaded into the boiler shell. The construction thus presents the terminal boiler-connections in each case at right angles to the intervening return-bend; so that the terminal and indeed all the joints are entirely relieved of the ill effects of expansion and contraction; and also one made up of materials easily obtainable in the market and adapted to be cut,

fitted, and put together, without special skill,

and applied without taking the boiler apart or removing it from its foundations. In preferred form, as hereinafter. shown, the horizontal connection to the water leg is a tube in two parts, abutted end to end, and secured by an ordinary screw collar: but this may be a single tube oppositely'threaded at the endsalternative constructions common in the art.

My invention is illustrated in the accompanying drawings, in which- Figure 1, is an under plan of a vertical flue boiler to which my invention is applied. Fig. 2, is a partial axial section showing my improvement in front elevation: and Fig. 3, is a detail side elevation of my improvement,

Referring now to the drawingsz-A, designates a vertical boiler of the common fire-box type, having flues, 01;,f01 the passage of combustion-products through the water-space of the boiler overlying the crown-sheet, b. As the flues, a, constitute the principal variable element of the heating surface, the steaming capacity of the boiler is in proportion to their number; and in boilersdesigned for quick and abundant generation of steam, the number of such fines is increased as much as practicable, while the diameter of the boiler is enlarged to increase the grate surface.

These conditions, as will readily be seen, tend to impede the free circulation of water over only by the presence of the tubes, but also by the intense heat transmitted to the water passing between them. To remedy these conditions, I omit the central one or more of the flues,a; and,inthecrown-sheetopening at that point, I attach one end of a water-tube connection, C, extending thence through the combustion-chamber of the fire-box, B, to the water leg, to, of the boiler. The tube, 0, thus forms a free and unobstructed water-connection between the part of the interior surface of the crown-sheet exposed to greatest heat and the outer and relatively coolest portion of the boiler. The demand for increased Water-circulation over the crown-sheet is therefore freely supplied at the point where most needed.

In constructing the connection, 0, I first insertin the crown-sheet, b, a nipple, c, to which, at right angles, is attached a return bend, c placed in an inclined position as shown in Fig 2, to facilitate the upward movement of water. At the free end of the return bend, the connection pipe, 0 is attached, at right angles, and thence enters the vertical shell of the fire-box, B. The connection pipe 0 may be a single pipe-section oppositely threaded at its ends and inserted in correspondingly threaded apertures, or it may be composed of two abutting sections of pipe connected by a screw-threaded collar c -both constructions being commonly used in the art and making detachablejoints. It willbe readily seen that the expansion of the connection tubes is accommodated by the natural elasticity of the metal disposed in long right-angled connections, without straining the joints at the crown-sheet or the water leg: while at the same time, additional heating surface is offered, and the rapidity of the flow through the connection, 0, increased thereby.

If desired, an additional number of connections, 0, may be employed according to the dimensions of the boiler, reaching the central portion of the crown-sheet and connecting thence to opposite radial portions of the water leg.

I claim as my invention and desire to secure by Letters Patent of the United States- 1. In a fire-box steam-boiler, one or more circulating tubes consisting of straight sections of tubing united by curved elbow-connections to present a vertical entrance into the crown sheet and a horizontal entrance into the watenleg, with an intervening horizontal return bend placed at an angle to the horizontal connection, substantially as set forth.

2. In a fire-box steam boiler, a circulating pipe consisting essentially of two horizontal parallel pipe-sections united at one end by a U-coupling to form a return bend, one end of said return bend being connected by an elbow vertically to the center of the crown sheet, and the other end by an elbow and detachable pipe-section horizontally to the water-leg, substantially as set forth.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

CHRISTOPHER AIIRENS.

Witnesses:

L. M. I-IOSEA, L. C. HOSEA. 

